IDLE CHANGES WHEN WEATHER IS COLD

[RonnieHarry750]

When the temperature drops pretty cool my 1995 Nighthawk increases rpms at idle when driving. Normal is 1000 then it jumps up to 1800 to 2000. Is this common or is there another issue with the quad carbs? It does not do it when it is warm outside, like 75 or more degrees. You would think with a 2 cable throttle this should not happen. Any thoughts?

 

[Biebs]

CAI - Cold Air Intake
Air is denser and will cause a leaner mixture which will increase the idle speed - 100 to 200 rpm at the most.

BUT - not by 800 to 1000 rpm!!

you might have a sticky throttle cable, needle, or slide that when warm unsticks.

Keep in mind these days fuel injection gets inputs to adjust for temperature, the carburetor while good in its time is a crude compromise for temperature and elevation.

 

[RonnieHarry750]

CAI - Cold Air Intake
Air is denser and will cause a leaner mixture which will increase the idle speed - 100 to 200 rpm at the most.

BUT - not by 800 to 1000 rpm!!

you might have a sticky throttle cable, needle, or slide that when warm unsticks.

Keep in mind these days fuel injection gets inputs to adjust for temperature, the carburetor while good in its time is a crude compromise for temperature and elevation.

Thanks, I had similar thoughts. When I rescued it a few months ago, had sat in weather for 3 years, not cranked since 2013. Did total rebuild on carbs except needle diaphragms, just don't want to disassemble again, even with new O-rings getting it all to seal back up was a pain. Runs like a demon but the idle issue makes me nervous. Cables working properly. Again, thanks for your input.